Embodiments of the present embodiments relate to a power supply protection circuit to temporarily maintain a functional power supply level for an integrated circuit in the event of power failure.
Power failure in integrated circuits may occur for a variety of reasons including external power failure, faulty battery contacts, sudden shock to portable devices such as dropping a cell phone, or circuit failure due to hardware or software problems. Power failure is often harmless, and integrated circuits are typically designed to provide an orderly shut down when a power failure is detected. This, however, may require large decoupling capacitors to maintain a functional power supply level and may be inadequate in the event of critical circuit operations. For example, if a power failure occurs during a write operation in a nonvolatile memory, data may be lost. Likewise, if a power failure occurs during transmission of a data frame, data may be lost. If a power failure occurs during a transfer of control in a processor circuit, a jump or subroutine call instruction may produce an incorrect address in an instruction pointer, thereby causing the processor circuit to “hang up.” Alternatively, if a power failure occurs during a disk write operation, incorrect data may be written to the disk resulting in a corrupt data file. Unexpected power failure in electronic devices, therefore, tends to cause temporary or permanent data loss in a wide variety of electronic devices.